There's some precedent for this. Even in 0e, saving throws eventually slowed their rate of improvement, and +1d6 HP per level eventually becomes +2 hp per level, which I suppose is slightly less. But by then, the PCs have already killed kings and tea-bagged tyrannosaurs. I want a small, powerful little system that plateaus early.
For this to work, HP, skills, and attack bonuses cannot advance linearly. I need a way for skills to be reined in heavily beyond third (?) level, but still easy to obtain at level 1 and 2 (because players like their level 1 thief to be mechanically differentiated than the other level 1 thief in the party).
I can think of two ways to do this.
